The Energy Star for UPS Program

The Environmental Protection Agency (EPA) is working overtime to make our data center more efficient. The ink is still wet on the Energy Star for Data Centers program, scheduled to be published on June 7. The EPA just held an Energy Star for UPS stakeholder conference on March 24 to provide a progress update and request for stakeholder comments (both manufacturers and users), due by April 2.

So what does this really mean to data center operators? Not very much to newer large sites that are already in operation, because they are unlikely to replace their uninteruptable power supply (UPS) equipment. However, for older, small to mid-size data centers, it may prompt them to review their existing UPS efficiency because the new guidelines will highlight the efficiency ratings of newer UPS hardware. One of the good things that the Energy Star for UPS program recognized (and presumably learned during the Energy Star for Data Centers program) is that it is not just the UPS manufacturer's published efficiency rating that will impact its actual efficiency in operation.

In point of fact, many data center UPSes operate at less than 50 percent on their rated load (a given in a 2N design), but in many cases they operate at less than 30 percent of their rated maximum for a majority of their operational life. This is usually due to the fact that large systems are purchased and installed day one, based the maximum rating of the data center. Older UPSes in particular are extremely inefficient at these lower power levels. Perhaps the EPA should consider a 'Cash for UPS Clunkers' program, since some of the systems are 15 years old and still going.

One of the goals of the EPA program is to address this by requiring manufacturers to publish the efficiency curve at all load levels, not just 90 percent or 100 percent. This will hopefully have two positive effects:

The manufacturers will be motivated to engineer a UPS with improved efficiency across a wider load range, instead of just publishing single a 9x percent rating (usually at 100 percent load or at their best efficiency point).

It will also make designers and users of UPS systems be more aware of the issue and motivate them to make better choices.

This would include specifying modular expandable UPS systems, or purchasing, installing and operating multiple UPS systems on a parallel system bus, designed as a scalable system. This would ensure that as the data center's energy requirements grew, more UPSes could be brought online to meet the load in a way that enables energy efficiency optimization throughout the varying load cycle because each UPS would operate in its higher efficiency range.